Hello UTH ,



I am trying to diagnose/fix a CEL that has been on for a few months now. After thorough searches in the UTH forum, I have tried several fixes... but the CEL comes on after a few driving cycles. The idle is sometimes rough, but overall the car runs fairly smooth. My car is stock, other than a K&N stock filter. It is a MY00 and has 87k miles.

Here's a list of fixes that I have tried:

1. New Spark Plugs
Replaced spark plugs with new NGK's stated in the TSB. After driving around 50-100 miles, the light came back on.

2. New Fuel Injectors
After reading Random1's thread about fuel injectors, I replaced all 4 of them. I noticed that the throttle response was smoother with less shaking at idle, but the CEL eventually came back on before 100 miles.

3. Cleaned the IAC valve
I found another thread about someone's s2000 getting random misfire's caused by carbon deposits in the IAC valve. Using intake cleaner, I removed the carbon deposits, reset the ECU...but the CEL came back on.

4. New PCV Valve
Since the CEL usually came on at idle, I replaced the PCV valve. I was not really convinced this was the cause of the problem, but tried it anyways. After driving less than 20 miles, the CEL came back on.

5. Compression Test
I read someone's advice about trying a compression and leak down test. Here are the results from the compression test (actron gauge from pep boys, average from 3 tests with 10 cycles each):

FROM THE FRONT OF THE CAR TO THE DRIVERS SEAT

Cylinder 1 = 220
Cylinder 2 = 250
Cylinder 3 = 235
Cylinder 4 = 235

I read that a variation from max to min should be no more than 10%, or if the PSI is above 200, it is fine? My max to min variation is a little above 10%, so I am not sure if I should worry about cylinder 1(or what to do?). I plan on adding a teaspoon of oil to cylinder 1 and trying the compression test again, to make sure it there is no seal leak.

Based on the compression test, should I be worried about bent/burnt valves?


6. Several MAP whacks with tiedowns
On another thread, I read that the connectors to the MAP sensor can come loose due to the vibrations in the engine. So I tried the MAP whack, and added tiedowns to secure it. After relearning the ECU, the CEL would come back on.



I am currently in the process of borrowing a friends air compressor and leak down tester, so I will try a leak down test this weekend. Other than that, I am out of ideas on what to try next.


Please help! I am stumped

 

Maybe a new MAP sensor?

Did you check that your spark plugs haven't come loose?

Also maybe coil packs.

 

when was the last time you got a valve adjustment?

 

Hi Ckit / Enthralled,

I was hoping the tiedown will "fix" any issues with the MAP sensor, but I will buy a brand new one and see if that works.

For the spark plugs being loose, I used a torque wrench everytime I reinstalled the spark plugs to 18 ft/ pounds. The spark plugs were never loose when I tried to uninstall them, so I do not think they were loose.

I tried to move around the coil packs, but I still get the random misfires. I am thinking all 4 coil packs would not go bad at once, so I ruled that out. Do you know of a way to test individual coil packs?

Enthralled, the car has never had a valve adjustment. Could a valve adjustment fix random misfire problems?

I am not sure when the car needs a valve adjustment, but I will try that soon.

Thanks for your help! I will try these fixes, and see if they work. If you can think of anything else, please let me know.

 

what codes are you getting?
I had P0301,P0304,P0300. One time they went away.
My cel came back with stall at idle, clutch in.
I cleared codes and they did not come back, and the stall was still there.
I ( I noted when I pulled plugs 1 and 4 did not look normal color. )
I went fm cel to stall at lite, clutch in.
Took to dealer and diagnosis said poor compression in cyl 1 and 4.
Bad exhaust valves, cyl 1 and 4. They are changing the head.
I hope to get back Sat.
Hopefully you do not have same problem.
PM if you want follow up.

 

man....we all been having the same problem... i'll be taking my car to the dealer monday and see what they say.

i get back to you guys about it.

what about you guys. heard anything yet?

 

any update?

 

I had this problem with my 00, and one of the coil packs was bad.

 

Replace the MAP yet? Also maybe an O2 sensor going bad?

We need the CEL #'s to have a better idea. Also do the valve adjustment, it's not hard and requires only to buy some feeler gauges. I am pretty sure there is an excellent walk through in the stickies.

 

i'm with Dirtybird,

have u tried swapping coil packs? cuz that's the first thing i would have swapped it's easy